From blue-green algae to
the bald eagle, there are over a million known species on our planet
Earth. This amazing array of life, or biodiversity, is everywhere you
look—its even in places you cant see, like deep underground.

Wherever theyre found,
all living things are related because they all share a common ancestor.
To show how species are related, scientists create diagrams called cladograms.
Like a family tree, a cladogram shows close and distant relatives. Scientists
call the family tree for all species on Earth the "Tree of Life."